Here’s how it works. Before connecting an Eye-Fi card to a Wi-Fi network, you have to load the network name and passcode from your computer using the software that comes with the card. Then, the card will automatically search for those networks whenever the camera is turned on. If you're in range, the card will connect and upload your pictures.

All the Eye-Fi cards work on your home network. The Explore Video and Pro cards also come with a year of free service to the more than 10,000 Wayport hotspots across the country ($15 per year after that). However, Eye-Fi cards won’t work with other public Wi-Fi hotspots or paid hotspot that require a Web browser to sign in.

In addition to wireless uploads to your computer, most Eye-Fi cards support automatic uploading to photo sharing sites (25 are supported) and the Explore Video and Pro cards also use geotagging to tag photos with your location.

One concern we have with the Eye-Fi card is the toll it can take on your camera’s battery. If the card detects your home network or a hotspot, it will remain connected via Wi-Fi for for as long as the camera is on. This can be a problem if you're shooting photos at home, say for your child's birthday party. Most of the time, the card will not be connected to a network so the impact on your camera’s battery life should be minimal. A few cameras can now detect when an Eye-Fi card has been inserted. These Eye-Fi connected cameras display upload progress as files are synced, and have optimized Eye-Fi power settings to lessen the impact on battery life.

If the convenience of having your photos appear on your computer or Flickr account without any effort on your part holds some appeal and you don’t mind a slight decrease in battery life, the Eye-Fi cards are definitely worth looking into.

Eye-Fi Explore Video ($100) 4GB of storage plus video transfer, the ability to upload your images to sharing sites, geotagging and one year unlimited uploads from 10,000 Wi-Fi hotpots.Buy Now

Eye-Fi Pro ($150) 4GB of storage plus video transfer, the ability to upload your images to sharing sites, geotagging, one year unlimited uploads from 10,000 Wi-Fi hotpots and support for a direct wireless connection to your computer, otherwise known as ad hoc networking.Buy Now